This small business innovation research Phase I project will utilize the controllable ion exchange properties of mixed metal oxides to efficiently separate radiostrontium from calcium (and other alkaline earth metals). The ion exchange properties of hydrous metal oxides can be tailored by systematically changing the synthetic variables to obtain a desired selectivity. It is proposed to develop a 'custom synthesized' cation exchanger designed to selectively separate 90Sr and Ca in acidic to neutral conditions in order to improve the separation methodology used in routine monitoring and detection of the radiocontaminant Sr in groundwaters as well as in biological and environmental samples. This need has been revealed by the constant need faced by DOE to treat groundwater contaminated by radioisotopes in efforts to prevent further contamination of ddnking water and eventually the food chain to humans, and the increased threat of possible terrorist attacks involving radioactive releases. The use of a highly selective inorganic ion exchange material to treat groundwater or in determination of 90Sr in acidified biological and environmental samples will result in considerable reductions in the analysis time and improvements in separation efficiency (lifetime of the system). An advantage will also be a decrease in the amount of spent exchanger and solid radioactive waste which will require safe disposal. The content of 90Sr in groundwater can effectively be reduced to below the EPA ddnking water limit and the material will be applicable to any effluent stream where there is a need to extract strontium in the presence of other alkaline earth metals. This is not limited to treating groundwater and monitoring drinking water, and natural samples, but can also be adapted to treatment of many nuclear waste solutions.